A category of fishing reels known commonly as SPINCASTING REELS or CLOSED-FACE SPINNING REELS has as a common feature a sheet-formed and substantially cup-shaped rotor device.
For improved clarity, the following discussion mentions only spincasting reels, but leaves it understood that the descriptions apply to all reels in the broader category.
The typical rotor of a spincasting reel substantially encircles the reel's spool and by certain related mechanisms serves to either release line from the spool for casting a lure or to rewind the line back onto the spool after a lure has been cast.
From the earliest development of spincasting reels, various parts and mechanisms have been attached to the rotor to improve its performance, but in all cases the rotor has retained its primary release and rewind functions. Common to all spincasting reel rotor designs has been their substantially cup-shaped structure which has always been formed by various known processes from a single sheet of material, most often steel.
The following descriptions refer only to steel rotors, but leave it understood that the description applies to any sheet-formed rotor structure.
The primary advantages of steel rotors are as follows:    1. Steel rotor surfaces and their formed edges are severely rubbed and abraded by fishing line as it is cast or retrieved from spincasting reels. These steel edges and surfaces are of a solid and slippery nature and cannot be easily damaged or abraded by the continuous friction of the fishing line.    2. Steel rotors are strong enough to permit a simple keyed-hole attachment to the main shaft of the reel to hold the rotors rotatably fixed thereto.
The primary disadvantages of steel rotors are the following:    1. Steel rotors are heavy. Because the gauge of the steel used to form the rotor must be thick enough to insure proper strength of the rotor, the rotor weight represents a substantial portion of a spincasting reel's total weight.    2. Steel rotors are costly. Sheet-forming steel forces costly manufacturing processes and the weight of the material forces a high material cost.    3. The related mechanisms that attach to and function with the rotor must be designed and manufactured in special ways to attach them to the steel sheet of the rotor.    4. The sheet-formed rotor must be punched or pressed-formed or otherwise prepared to receive these related mechanism attachments. This preparation forces increased processing cost and forces undesirable production and assembly difficulties.